Field test of a geogrid-reinforced and floating pile-supported embankment

A well-designed field experiment was carried out to enhance the understanding of a geogrid-reinforced and floating pile-supported (GRFPS) embankment constructed on alluvial soil with medium-low compressibility (ASMLC). Two test sections with identical reinforcement solutions and fill load were chosen for field monitoring which lasted approximately 32 months. The measurements, including pore water pressure, settlement, soil stress, strain in geogrid, and lateral displacement during and after the embankment filling, were reported and the performance of GRFPS embankment was examined. The results indicate that the downward movement of the floating pile allowed the fill load to transfer from the pile (cap) to the subsoil and mobilised more counter support from the subsoil. Less soil arching effect and tensioned membrane effect were observed, and so were the stress concentration ratio and strain in the geogrid. The floating pile with limited embedment depth is sufficient to control both the total settlement and lateral displacement. The existing design procedures are expected to be overly conservative for GRFPS embankment constructed on alluvial soil with medium-low compressibility, and some recommendations are proposed to help with the design.